However, questions are frequently raised about their accuracy since
their speciation can often be changed quickly as a result of chemical,
biological and physical reactions. Furthermore, these sampling
methods can be generally tedious and time consuming [10]. The
time delays associated with this procedure are frequently unacceptable.
Thus, it is desirable to prevent the sample alterations
associated with the transport delays by performing analyses rapidly
and on-site, which is a crucial issue in environmental monitoring. A
significant advantage of microelectromechanical system (MEMS) is
the ability tomakepossible mechanical parts of micron size that can
use very small volumes (a fewL). In addition, the mass production
ability of MEMS technology, due to its batch fabrication methods,
permits use of low cost components with high accuracy and reliability,
which are vital for effective sample mixing, separation, etc.
The use of lab chip concept enables miniaturized instruments for
detecting nitrate, pH and heavy metals in the surface waters and
groundwater at shallow depths.